Solid-state imaging device, manufacturing method thereof, and electronic apparatus

ABSTRACT

A solid-state imaging device includes a plurality of photoelectric conversion portions each provided to correspond to each of a plurality of pixels in a semiconductor substrate and receiving incident light through a light sensing surface, and a pixel separation portion that is embedded into a trench provided on a side portion of the photoelectric conversion portion and electrically separates the plurality of pixels in a side of an incident surface of the semiconductor substrate into which the incident light enters. The pixel separation portion is formed by an insulation material which absorbs the incident light entering the light sensing surface.

BACKGROUND

The present disclosure relates to a solid-state imaging device, amanufacturing method thereof, and an electronic apparatus.

Electronic apparatuses such as a digital video camera or a digital stillcamera include a solid-state imaging device. For example, thesolid-state imaging device includes a CCD (Charge Coupled Device) typeimage sensor or a CMOS (Complementary Metal Oxide Semiconductor) typeimage sensor.

In the solid-state imaging device, a plurality of pixels are arranged ona pixel region of a substrate. A photoelectric conversion portion isprovided on each pixel. For example, the photoelectric conversionportion is a photodiode, and receives incident light through the lightsensing surface and generates a signal charge by performing aphotoelectric conversion with respect to the received light.

Among the solid-state imaging devices, in the CCD type image sensor, avertical transfer portion is provided between a plurality of pixelcolumns which are vertically lined up in a pixel region. In the verticaltransfer portion, a plurality of transfer electrodes are provided so asto be facing a vertical channel region through gate insulating films,and the vertical transfer portion is configured so as to transfer thesignal charge, which is read from the photoelectric conversion portionby a charge readout portion, in a vertical direction.

In contrast, in the CMOS type image sensor, pixels are configured so asto include a pixel transistor in addition to the photoelectricconversion portion. The pixel transistor is configured so as to read thesignal charge generated by the photoelectric conversion portion andoutput the read signal charge to a signal line as an electric signal.

In general, in the solid-state imaging device, the photoelectricconversion portion receives light incident from a front surface side onwhich circuit elements, wirings, or the like are provided in asubstrate. In the cases of the “front surface illumination type”, sincethe circuit elements or wirings shield the incident light, it may bedifficult to improve sensitivity.

Thereby, “a rear surface illumination type” has been suggested in whichthe photoelectric conversion portion receives the light incident from arear surface side which is a side opposite to the front surface on whichthe circuit elements, the wirings, or the like are provided in thesubstrate. Also in the “rear surface illumination type”, the incidentlight entering one pixel may not enter the photodiode of this one pixeland enter photodiodes of adjacent other pixels. For example, when theincident light enters in a largely inclined state, the light does notenter the photodiode of the pixel just below the light and enters thephotodiodes of other pixels. Thereby, since noise is included in thesignal due to the optical phenomenon, quality of the captured image maybe decreased. In order to suppress occurrence of this disadvantage,light shielding films are provided between a plurality of pixels (forexample, refer to Japanese Unexamined Patent Application PublicationNos. 2010-109295 and 2010-186818).

Moreover, in the solid-state imaging device, in order to suppress a darkcurrent from being generated due to an interface state of thesemiconductor substrate on which the photoelectric conversion portion isprovided, the photoelectric conversion portion of an HAD (HoleAccumulation Diode) structure has been suggested. In the HAD structure,since a positive charge (hole) accumulation region is formed on a lightsensing surface of a n-type charge accumulation region, occurrence ofthe dark current is suppressed. In addition, in order to form thepositive charge accumulation region in the interface portion of thephotoelectric conversion portion, further suppressing occurrence of thedark current by providing “a film having a negative fixed charge” as apinning layer has been suggested. For example, a high dielectricconstant film such as a hafnium oxide film (HfO₂ film) is used as the“film having a negative fixed charge” (for example, refer to JapaneseUnexamined Patent Application Publication No. 2008-306154 or the like).

Moreover, in the solid-state imaging device, in order to prevent thesignal outputs from each pixel from being mixed due to electric noise, apixel separation portion which electrically separates a plurality ofpixels is provided. For example, the pixel separation portion isprovided by ion-implanting impurities to the semiconductor substrate.

SUMMARY

FIG. 27 is a cross-sectional view illustrating a main portion of a pixelP in the CMOS image sensor of the “rear surface illumination type”.

As illustrated in FIG. 27, in the CMOS image sensor of the “rear surfaceillumination type”, a photodiode 21 is provided in a portion which isdivided by a pixel separation portion 101 pb in the inner portion of asemiconductor substrate 101. In the photodiode 21, an n-type impurityregion 101 n is provided as a charge accumulation region. The photodiode21 is an HAD structure, and the n-type impurity region 101 n is formedso as to be interposed between p-type semiconductor regions 101 pa and101 pc in the depth direction z of the semiconductor substrate 101.

Although not illustrated in FIG. 27, a pixel transistor is provided onthe front surface (lower surface in FIG. 27) of the semiconductorsubstrate 101, and as illustrated in FIG. 27, a wiring layer 111 isprovided so as to cover the pixel transistor. The wiring layer 111 isformed so that wirings 111 h are covered by an insulating layer 111 z.In addition, a supporting substrate SS is provided on the front surface(lower surface) of the wiring layer 111.

In contrast, a light shielding film 60, a color filter CF, and amicrolens ML are provided on the rear surface (upper surface in FIG. 27)of the semiconductor substrate 101, and the photodiode 21 receives theincident light H which enters via each of the portions.

Here, as illustrated in FIG. 27, for example, the light shielding film60 is formed on the upper surface of the semiconductor substrate 101 viaan insulating film SZ which is a silicon oxide film. The light shieldingfilm 60 is provided above the pixel separation portion 101 pb providedin the inner portion of the semiconductor substrate 101, and the upperportion of a light sensing surface JS is opened. For example, the lightshielding film 60 is formed by using a light shielding material such asmetal.

Moreover, the upper surface of the light shielding film 60 is covered bya planarized film HT, and the color filter CF and the microlens ML areprovided on the upper surface of the planarized film HT. For example, inthe color filter CF, each filter layer of three primary colors isarranged for each pixel P by a Bayer array.

When manufacturing the solid-state imaging device, first, the photodiode21 and the pixel separation portion 101 pb are formed by ion-implantingimpurities from the front surface side (lower surface side in FIG. 27)of the semiconductor substrate 101. Moreover, after members such as thepixel transistor (not illustrated) or the like are formed on the frontsurface (lower surface) side of the semiconductor substrate 101, thewiring layer 111 is formed so as to cover the front surface (lowersurface). Moreover, the supporting substrate SS is bonded onto the frontsurface (lower surface) of the wiring layer 111. Thereafter, afilm-thinning treatment is performed in which the rear surface (uppersurface) side of the semiconductor substrate 101 is grounded. Moreover,each of members such as the insulating film SZ, the light shielding film60, the planarized film HT, the color filter CF, and the microlens ML issequentially provided on the rear surface (upper surface) side of thesemiconductor substrate 101. In this way, the solid-state imaging deviceis manufactured.

In the solid-state imaging device, the light shielding film 60 is formedon the rear surface (upper surface) of the semiconductor substrate 101,and the incident light H entering one pixel P may be transmitted belowthe light shielding film 60 and may enter the photodiode 21 of anotheradjacent pixel P. For example, when the incident light H enters in alargely inclined state, the incident light H may pass through the pixelseparation portion 101 pb which is formed by the ion implantation ofimpurities and may enter the photodiode 21 of the other adjacent pixelP. Moreover, similarly, irregularly reflected light may enter thephotodiode 21 of the other pixel P. Thereby, so-called “color mixing”may be generated, color reproducibility in the captured color image maybe decreased, and the image quality may be decreased.

In the “rear surface illumination type” solid-state imaging device, thelight H incident from the rear surface (upper surface) side of thesemiconductor substrate 101 enters the light sensing surface JS of thephotodiode 21. Thereby, the “color mixing” is often generated in thevicinity of the rear surface (upper surface) of the semiconductorsubstrate 101.

As described above, in the “rear surface illumination type” solid-stateimaging device, the pixel separation portion 101 pb is formed byion-implanting impurities with a high energy from the front surface side(lower surface side in FIG. 27) of the semiconductor substrate 101 andperforming an annealing treatment. Thereby, in the rear surface (uppersurface) side of the semiconductor substrate 101 into which the incidentlight H enters, since the impurities which are ion-implanted from thefront surface (lower surface) side are dispersed in a transversedirection, as illustrated in FIG. 27, the width of the pixel separationportion 101 pb is formed to be widened to the rear surface (uppersurface) side. Thereby, the electric field in the transverse directionis weak in the rear surface (upper surface) side of the semiconductorsubstrate 101 (refer to Japanese Unexamined Patent ApplicationPublication No. 2003-318122). Therefore, due to this, the “color mixing”may be more often generated in the vicinity of the rear surface (uppersurface) of the semiconductor substrate 101.

Particularly, a charge generated by the pixel which receives a shortwavelength light such as blue may move to the adjacent pixels whichreceive the light of the other color, and occurrence of the “colormixing” may be obvious. This is due to the fact that light having theshorter wavelength is absorbed in the vicinity of the rear surface(upper surface) into which the light enters in the semiconductorsubstrate 101 configured of a single crystal silicon semiconductor.

Besides this, as described above, since the width of the pixelseparation portion 101 pb is widened, it may be difficult to widen theoccupancy area of the photodiode 21. Therefore, a saturation chargeaccumulation amount (Qs) of the photodiode 21 is decreased, a dynamicrange is deteriorated, and in some case, it is difficult to improve thequality of the captured image.

Occurrence of the above described disadvantages is not limited to thecase of the “rear surface illumination type” and may be generated in thecase of the “front surface illumination type” solid-state imagingdevice.

In the case of the “front surface illumination type”, since impuritiesare ion-implanted from the front surface side into which the incidentlight enters in the semiconductor substrate and the pixel separationportion is formed, the width of the pixel separation portion is widenedand formed in the deeper portion from the front surface. In addition, inthe semiconductor substrate configured of a single crystal siliconsemiconductor, the light having a shorter wavelength is absorbed in thevicinity of the front surface into which the light enters. However, thelight having a longer wavelength reaches the deeper portion of thesemiconductor substrate. Thereby, particularly, since it is difficult toimprove the saturation charge accumulation amount (Qs) of the pixelwhich receives the light having a longer wavelength such as red, qualityof the captured image may not be easily improved.

In this way, in the solid-state imaging device, improvement of qualityof the captured image may be difficult.

Therefore, it is desirable to provide a solid-state imaging device, amanufacturing method thereof, and an electronic apparatus capable ofimproving quality or the like of a captured image.

According to an embodiment of the present disclosure, there is provideda solid-state imaging device which includes a plurality of photoelectricconversion portions each provided to correspond to each of a pluralityof pixels in a semiconductor substrate and receiving incident lightthrough a light sensing surface, and a pixel separation portion that isembedded into a trench provided on a side portion of the photoelectricconversion portion and electrically separates the plurality of pixels ina side of an incident surface of the semiconductor substrate into whichthe incident light enters, and the pixel separation portion is formed byan insulation material which absorbs the incident light entering thelight sensing surface.

According to another embodiment of the present disclosure, there isprovided a method of manufacturing a solid-state imaging device whichincludes providing a plurality of photoelectric conversion portionswhich receive incident light through a light sensing surface so as tocorrespond to a plurality of pixels in the semiconductor substrate, andforming a pixel separation portion that electrically separates theplurality of pixels so as to be embedded into a trench provided on aside portion of the photoelectric conversion portion in a side of anincident surface of the semiconductor into which the incident lightenters, and the pixel separation portion is formed by an insulationmaterial which absorbs the incident light entering the light sensingsurface when forming the pixel separation portion.

According to another embodiment of the present disclosure, there isprovided an electric apparatus which includes a plurality ofphotoelectric conversion portions each provided to correspond to each ofa plurality of pixels in a semiconductor substrate and receivingincident light through a light sensing surface, and a pixel separationportion that is embedded into a trench provided on a side portion of thephotoelectric conversion portion and electrically separates theplurality of pixels in a side of an incident surface of thesemiconductor substrate into which the incident light enters, and thepixel separation portion is formed by an insulation material whichabsorbs the incident light entering the light sensing surface.

According to the present disclosure, it is possible to provide asolid-state imaging device, a manufacturing method thereof, and anelectronic apparatus capable of improving quality or the like of thecaptured image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration diagram illustrating a configuration of acamera in a first embodiment of the present disclosure.

FIG. 2 is a diagram illustrating the entire configuration of asolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 3 is a diagram illustrating a main portion of the solid-stateimaging device in the first embodiment of the present disclosure.

FIG. 4 is a diagram illustrating a main portion of the solid-stateimaging device in the first embodiment of the present disclosure.

FIG. 5 is a diagram illustrating a main portion of the solid-stateimaging device in the first embodiment of the present disclosure.

FIG. 6 is a timing chart illustrating a control signal which is sent toa pixel transistor Tr of a pixel P when performing an imaging in thefirst embodiment of the present disclosure.

FIG. 7 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 8 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 9 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 10 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 11 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 12 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 13 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

FIG. 14 is a graph illustrating a refractive index of single crystal Si.

FIG. 15 is a graph illustrating a refractive index and extinctioncoefficient of a SiN film.

FIG. 16 is a graph illustrating a FTIR (Fourier Transform Infraredabsorption) spectrum of the SiN film.

FIG. 17 is a graph illustrating a transmissivity of a photosensitiveresin containing a black pigment.

FIGS. 18A to 18C are graphs illustrating a transmissivity of aphotosensitive resin containing a primary color system pigment.

FIGS. 19A to 19C are graphs illustrating a transmissivity of aphotosensitive resin containing a complementary color system pigment.

FIG. 20 is a diagram illustrating a main portion of a solid-stateimaging device in a second embodiment of the present disclosure.

FIG. 21 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure.

FIG. 22 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure.

FIG. 23 is a diagram illustrating a method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure.

FIG. 24 is a diagram illustrating a main portion of a solid-stateimaging device in a third embodiment of the present disclosure.

FIG. 25 is a diagram illustrating a main portion of a solid-stateimaging device in a fourth embodiment of the present disclosure.

FIG. 26 is a diagram illustrating a main portion of a solid-stateimaging device in a fifth embodiment of the present disclosure.

FIG. 27 is a cross-sectional diagram illustrating a main portion of apixel P in a CMOS image sensor of “a rear surface illumination type”.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described with referenceto the drawings.

In addition, description is performed in the following order.

1. First Embodiment (Case where Pixel Separation Portion is SingleLayer)

2. Second Embodiment (Case where Pinning layer is Provided in Peripheryof Pixel Separation Portion)

3. Third Embodiment (Case where Pixel Separation Portion Includes TwoDifferent Light Absorption Portions)

4. Fourth Embodiment (Case where Pixel Separation Portion Includes ThreeDifferent Light Absorption Portions)

5. Fifth Embodiment (Case of Front Surface Illumination Type)

6. Others

1. First Embodiment

(A) Apparatus Configuration

(A-1) Main Portion Configuration of Camera

FIG. 1 is a configuration diagram illustrating a configuration of acamera 40 in a first embodiment of the present disclosure.

As illustrated in FIG. 1, the camera 40 includes a solid-state imagingdevice 1, an optical system 42, a control portion 43, and a signalprocessing portion 44. Each portion will be sequentially described.

The solid-state imaging device 1 receives incident light H, which entersas a subject image via the optical system 42, through an imaging surfacePS, performs a photoelectric conversion with respect to the receivedlight, and generates a signal charge. Here, the solid-state imagingdevice 1 reads the signal charge by being driven based on a controlsignal output from the control portion 43, and outputs an electricsignal.

The optical system 42 includes optical members such as an imaging lensor an aperture and is disposed so as to focus the incident light H onthe imaging surface PS of the solid-state imaging device 1.

The control portion 43 outputs various control signals to thesolid-state imaging device 1 and the signal processing portion 44, andcontrols and drives the solid-state imaging device 1 and the signalprocessing portion 44.

The signal processing portion 44 is configured so as to generate adigital image with respect to the subject image by performing a signalprocessing while having the electric signal output from the solid-stateimaging device 1 as a raw data.

(A-2) Main Portion Configuration of Solid-state Imaging Device

The entire configuration of the solid-state imaging device 1 will bedescribed.

FIG. 2 is a diagram illustrating the entire configuration of asolid-state imaging device 1 in a first embodiment of the presentdisclosure.

The solid-state imaging device 1 of the present embodiment is a CMOStype image sensor and includes a semiconductor substrate 101 asillustrated in FIG. 2. For example, the semiconductor substrate 101 maybe formed by thinning a single crystal silicon semiconductor substrate,and a pixel region PA and a peripheral region SA are provided on thesurface of the semiconductor substrate.

As illustrated in FIG. 2, the pixel region PA is a rectangular shape,and a plurality of pixels P are disposed in each of a horizontaldirection x and a vertical direction y. That is, the pixels P are linedup with a matrix form.

In the pixel region PA, the pixels P are configured so as to receive theincident light and generate the signal charge. Moreover, the generatedsignal charge is read by a pixel transistor (not illustrated) and outputas an electric signal. The detailed configuration of the pixels P willbe described hereinafter.

As illustrated in FIG. 2, the peripheral region SA is positioned in theperiphery of the pixel region PA. Moreover, a peripheral circuit isprovided in the peripheral region SA.

Specifically, as illustrated in FIG. 2, a vertical drive circuit 13, acolumn circuit 14, a horizontal drive circuit 15, an external outputcircuit 17, a timing generator (TG) 18, and a shutter drive circuit 19are provided as the peripheral circuit.

As illustrated in FIG. 2, the vertical drive circuit 13 is provided atthe side portion of the pixel region PA in the peripheral region SA, andthe vertical drive circuit is configured so as to select and drive thepixels P of the pixel region PA by a row unit.

As illustrated in FIG. 2, the column circuit 14 is provided at the lowerend of the pixel region PA in the peripheral region SA, and performs asignal processing with respect to the signal which is output from thepixels P by a column unit. Here, the column circuit 14 includes a CDS(Correlated Double Sampling) circuit (not illustrated) and performs asignal processing which removes a fixed pattern noise.

As illustrated in FIG. 2, the horizontal drive circuit 15 iselectrically connected to the column circuit 14. For example, thehorizontal drive circuit 15 includes a shift register, and sequentiallyoutputs the signal, which is held for each column of the pixels P in thecolumn circuit 14, to the external output circuit 17.

As illustrated in FIG. 2, the external output circuit 17 is electricallyconnected to the column circuit 14. In addition, after the externaloutput circuit 17 performs a signal processing with respect to thesignal output from the column circuit 14, the external output circuitoutputs the processed signal to the external. The external outputcircuit 17 includes an AGC (Automatic Gain Control) circuit 17 a and anADC circuit 17 b. In the external output circuit 17, after the AGCcircuit 17 a multiplies the signal by a gain, the ADC circuit 17 bconverts the analog signal to the digital signal and outputs theconverted signal to the external.

As illustrated in FIG. 2, the timing generator 18 is electricallyconnected to the vertical drive circuit 13, the column circuit 14, thehorizontal drive circuit 15, the external output circuit 17, and theshutter drive circuit 19 respectively. The timing generator 18 generatesvarious timing signals, outputs the signals to the vertical drivecircuit 13, the column circuit 14, the horizontal drive circuit 15, theexternal output circuit 17, and the shutter drive circuit 19. Therefore,the timing generator performs the driving control with respect to eachportion.

The shutter drive circuit 19 is configured so as to select the pixels Pby a row unit and adjust an exposure time in the pixels P.

(A-3) Detailed Configuration of Solid-state Imaging Device

The detailed contents of the solid-state imaging device according to thepresent embodiment are described.

FIGS. 3 to 5 are diagrams illustrating a main portion of the solid-stateimaging device in a first embodiment of the present disclosure.

FIG. 3 is a cross-sectional diagram of the pixel P. Moreover, FIG. 4 isa top view of the pixel P. In addition, FIG. 5 illustrates a circuitconfiguration of the pixel P. Moreover, FIG. 3 illustrates across-section taken along a line III-III illustrated in FIG. 4.Moreover, in FIG. 4, for convenience of description, in some cases,portions which illustrate each member are denoted by a broken line orthe like other than a solid line.

As illustrated in FIG. 3, the solid-state imaging device 1 includes aphotodiode 21 and a pixel separation portion 301 in the inner portion ofthe semiconductor substrate 101. For example, each portion is providedin the semiconductor substrate 101 of thinned single crystal silicon.

Members such as a light shielding film 60, a color filter CF, and amicrolens ML are provided on a rear surface (upper surface in FIG. 3) ofthe semiconductor substrate 101.

In contrast, although not illustrated in FIG. 3, a pixel transistor Trillustrated in FIG. 5 is provided on the front surface (lower surface inFIG. 3) of the semiconductor substrate 101. Moreover, as illustrated inFIG. 3, a wiring layer 111 is provided so as to cover the pixeltransistor Tr. In addition, in the wiring layer 111, a supportingsubstrate SS is provided on the surface of the side opposite to the sideof the semiconductor substrate 101.

That is, the solid-state imaging device 1 of the present embodiment is a“rear surface illumination type CMOS image sensor”, and is configured sothat the photodiode 21 receives the light H incident from the rearsurface (upper surface) and generates a color image by imaging.

Details of each portion will be sequentially described.

(a) Photodiode 21

In the solid-state imaging device 1, a plurality of photodiodes 21 aredisposed in the pixel region PA so as to correspond to the plurality ofpixels P illustrated in FIG. 2. That is, the plurality of photodiodes 21are provided so as to be lined up in each of a horizontal direction xand a vertical direction y perpendicular to the horizontal direction xin an imaging surface (xy plan).

The photodiode 21 is configured so as to generate signal charge byreceiving the incident light H and performing a photoelectric conversionof the received light and accumulate the generated signal charge.

Here, as illustrated in FIG. 3, the photodiode 21 receives the light Hincident from the rear surface (upper surface in FIG. 3) side of thesemiconductor substrate 101. As illustrated in FIG. 3, a planarized filmHT, a color filter CF, and a microlens ML are provided above thephotodiode 21, the incident light H, which enters sequentially via eachportion, is received through a light sensing surface JS, and aphotoelectric conversion of the received light is performed.

As illustrated in FIG. 3, for example, the photodiode 21 is provided inthe semiconductor substrate 101 which is a single crystal siliconsemiconductor.

For example, the photodiode 21 is formed as a charge accumulation regionin which an n-type semiconductor region 101 n accumulates a charge(electrons). In the photodiode 21, the n-type semiconductor region 101 nis provided in the inner portion of p-type semiconductor regions 101 paand 101 pc of the semiconductor substrate 101. Here, in the n-typesemiconductor region 101 n, the p-type semiconductor region 101 pc,which has a higher impurity concentration than the rear surface (uppersurface) side, is provided in the front surface (lower surface) side ofthe semiconductor substrate 101. That is, the photodiode 21 is an HADstructure, and the p-type semiconductor regions 101 pa and 101 pc areformed in each interface of the upper surface side and the lower surfaceside of the n-type semiconductor region 101 n in order to suppressoccurrence of a dark current.

As illustrated in FIG. 3, a pixel separation portion 301 whichelectrically separates the plurality of pixels P is provided in theinner portion of the semiconductor substrate 101, and photodiode 21 isprovided in a region which is divided by the pixel separation portion301. For example, as illustrated in FIG. 4, the pixel separation portion301 is formed in a lattice shape so as to be interposed between theplurality of pixels P, and the photodiode 21 is formed in the regionwhich is divided by the pixel separation portion 101 pb.

In addition, as illustrated in FIG. 5, an anode is grounded to eachphotodiode 21, and each photodiode 21 is configured so that theaccumulated signal charge (here, electrons) is read by a pixeltransistor Tr and output to a vertical signal line 27 as an electricsignal.

(b) Shielding Film 60

In the solid-state imaging device 1, as illustrated in FIG. 3, the lightshielding film 60 is provided on the rear surface (upper surface in FIG.3) side of the semiconductor substrate 101.

The light shielding film 60 shields a portion of the incident light Hfrom above the semiconductor substrate 101 toward the rear surface ofthe semiconductor substrate 101.

As illustrated in FIG. 3, the light shielding film 60 is provided abovethe pixel separation portion 301 which is provided in the inner portionof the semiconductor substrate 101. Here, the light shielding film 60 isprovided so as to be protruded in a convex shape via an insulating filmSZ such as a silicon oxide film on the rear surface (upper surface) ofthe semiconductor substrate 101. In contrast, the light shielding film60 is opened so as to be not provided above the photodiode 21 which isprovided in the inner portion of the semiconductor substrate 101 so thatthe incident light H enters the photodiode 21.

That is, as illustrated in FIG. 4, the planar shape of the light shieldfilm 60 is a lattice shape and includes an opening in which the incidentlight H passes through the light sensing surface.

The light shielding film 60 is formed of a light shielding materialwhich shields light. For example, the light shielding film 60 is formedby sequentially laminating a titanium (Ti) film and a tungsten (W) film.Besides this, the light shielding film 60 may be formed by sequentiallylaminating a titanium nitride (TiN) film and a tungsten (W) film.

Moreover, as illustrated in FIG. 3, the light shielding film 60 iscovered by a planarized film HT. The planarized film HT is formed byusing an insulation material which transmits light.

(C) Color Filter CF

In the solid-state imaging device 1, as illustrated in FIG. 3, the colorfilter CF is provided on the upper surface of the planarized film HT inthe rear surface (upper surface in FIG. 3) side of the semiconductorsubstrate 101.

As illustrated in FIG. 4, the color filter CF includes a red filterlayer CFR, a green filter layer CFG, and a blue filter layer CFB. Eachof the red filter layer CFR, the green filter layer CFG, and the bluefilter layer CFB is disposed so as to be adjacent to one another; thelayers are all provided so as to correspond to each of the plurality ofpixels P.

Here, as illustrated in FIG. 4, each of the red filter layer CFR, thegreen filter layer CFG, and the blue filter layer CFB is disposed so asto be lined up in a Bayer array. That is, a plurality of green filtersCFG are disposed so as to be lined up in the diagonal direction to be achecked pattern. Moreover, the red filter layer CFR and the blue filterlayer CFB are disposed so as to be lined up in the diagonal direction inthe plurality of green filter layers CFG.

Specifically, the red filter layer CFR is formed so as to have a higherlight transmissivity in a wavelength band (for example, 625 to 740 nm)corresponding to red, and to color the incident light H red and transmitthe colored light to the sensing surface JS.

Moreover, the green filer filter layer CFG has a higher lighttransmissivity in a wavelength band (for example, 500 to 565 nm)corresponding to green. That is, the green filter layer CFG is formed soas to have a higher light transmissivity with respect to the light ofthe wavelength range of the shorter wavelength than the wavelengthhaving the higher light transmissivity in the red filter layer CFR, andto color the incident light H green and transmit the colored light tothe light sensing surface JS.

In addition, the blue filer filter layer CFB has a higher lighttransmissivity in a wavelength band (for example, 450 to 485 nm)corresponding to blue. That is, the blue filter layer CFB is formed soas to have a higher light transmissivity with respect to the light ofthe wavelength range of the shorter wavelength than the wavelengthhaving the higher light transmissivity in the green filter layer CFG,and to color the incident light blue and transmit the colored light tothe light sensing surface JS.

(d) Microlens ML

In the solid-state imaging device 1, as illustrated in FIG. 3, themicrolens ML is provided on the upper surface of the color filter CF inthe rear surface (upper surface in FIG. 3) side of the semiconductorsubstrate 101.

A plurality of microlenses ML are disposed so as to correspond to eachpixel P. The microlens ML is a convex lens which is protruded in aconvex shape in the rear surface side of the semiconductor substrate101, and is configured so as to focus the incident light H to thephotodiode 21 of each pixel P. For example, the microlens ML is formedby using an organic material such as a resin.

(e) Pixel Separation Portion 301

In the solid-state imaging device 1, as illustrated in FIGS. 3 and 4,the pixel separation portion 301 is formed by an insulation material soas to divide between the plurality of pixels P and electricallyseparates the plurality of pixels P.

As illustrated in FIG. 3, the pixel separation portion 301 is formed soas to be embedded to the inner portion of the semiconductor substrate101 in the rear surface (upper surface in FIG. 3) side of thesemiconductor substrate 101.

Specifically, the p-type impurity regions 101 pa and 101 pc are providedbetween the n-type impurity regions 101 n which configure the chargeaccumulation region of the photodiode 21 between the plurality of pixelsP. Moreover, a trench TR is formed on the rear surface (upper surface)side of the p-type impurity regions 101 pa and 101 pc, and the pixelseparation portion 301 is provided in the inner portion of the trenchTR.

As illustrated in FIG. 4, the planar shape of the pixel separationportion 301 is a lattice shape and interposed between the plurality ofpixels P. In addition, the photodiode 21 is formed in the rectangularregion which is divided by the lattice shaped pixel separation portion101 pb.

Here, the pixel separation portion 301 is formed by an insulationmaterial which absorbs the light which enters the light sensing surfaceJS. The pixel separation portion 301 is formed so as to selectivelyabsorb the light having at least some wavelength ranges in light havinga plurality of different wavelength ranges which enters the lightsensing surface JS via the color filter CF.

In the present embodiment, the pixel separation portion 301 is formed soas to at least selectively absorb the light having the wavelength rangeof the shortest wavelength in light having a plurality of differentwavelength ranges which enters the light sensing surface JS via thecolor filter CF.

Specifically, among the colored light which is transmitted by the redfilter layer CFR, the green filter layer CFG, and the blue filter layerCFB, when the blue light having the wavelength range of the shortestwavelength enters the pixel separation portion 301, the pixel separationportion 301 is formed so as to selectively absorb the blue light. Thatis, in the solid-state imaging device 1, the pixel separation portion301 selectively absorbs the short wavelength light which is absorbed inthe vicinity of the rear surface of the semiconductor substrate 101 andin which the “color mixing” is significantly generated.

Moreover, the pixel separation portion 301 is formed of a material whichhas a refractive index different from that of the semiconductorsubstrate 101.

For example, the pixel separation portion 301 is formed by forming asilicon nitride film (SiN) through an ALD (Atomic Layer Deposition)method. Thereby, the pixel separation portion 301 can selectively absorbthe blue light. In addition, since the refractive index of the pixelseparation portion 301 is different from that of the semiconductorsubstrate 101, the incident light H is reflected at the interfacebetween the pixel separation portion 301 and the semiconductor substrate101. Moreover, the light reflected at the interface enters thephotodiode 21 again and the photoelectric conversion of the light isperformed.

In addition, as illustrated in FIG. 3, the light shielding film 60 isprovided above the pixel separation portion 301 via the insulating filmSZ. Here, as illustrated in FIG. 4, similarly to the pixel separationportion 301, the planar shape of the light shielding film 60 is formedso as to be a lattice shape.

(f) Pixel Transistor Tr

In the solid-state imaging device 1, a plurality of pixel transistors Trare disposed so as to correspond to the plurality of pixels illustratedin FIG. 2.

As illustrated in FIG. 5, the pixel transistor Tr includes a transfertransistor 22, an amplifying transistor 23, a selection transistor 24,and a reset transistor 25, and reads the signal charge from thephotodiode 21 and outputs the read signal charge as an electric signal.

Although not illustrated in FIG. 3, each of the transistors 22 to 25which configure the pixel transistor Tr is provided on the front surfaceon which the wiring layer 111 is provided in the semiconductor substrate101. For example, each of the transistors 22 to 25 is an N channel MOStransistor, and for example, each gate is formed by using polysilicon.Moreover, each of the transistors 22 to 25 is covered by the wiringlayer 111.

In the pixel transistor Tr, as illustrated in FIG. 5, the transfertransistor 22 is configured so as to transfer the signal charge, whichis generated by the photodiode 21, to a floating diffusion FD.Specifically, as illustrated in FIG. 5, the transfer transistor 22 isprovided between a cathode of the photodiode 21 and the floatingdiffusion FD. In addition, the gate of the transfer transistor 22 iselectrically connected to the transfer line 26. The transfer transistor22 transfers the signal charge, which is accumulated in the photodiode21, to the floating diffusion FD based on a transfer signal TG which issent from the transfer line 26 to the gate.

In the pixel transistor Tr, as illustrated in FIG. 5, the amplifyingtransistor 23 is configured so as to amplify the electric signalconverted from the charge to the voltage in the floating diffusion FDand output the amplified electric signal. Specifically, as illustratedin FIG. 5, the gate of the amplifying transistor 23 is electricallyconnected to the floating diffusion FD. Moreover, the drain of theamplifying transistor 23 is electrically connected to a power supplyline Vdd, and the source of the amplifying transistor is electricallyconnected to the selection transistor 24. When the selection transistor24 is selected so as to be turned on, a constant current is supplied tothe amplifying transistor 23 from a constant current source I, and theamplifying transistor is operated as a source follower. Therefore, dueto the fact that the selection signal is supplied to the selectiontransistor 24, the electric signal, which is converted from the chargeto the voltage in the floating diffusion FD, is amplified in theamplifying transistor 23.

In the pixel transistor Tr, as illustrated in FIG. 5, the selectiontransistor 24 is configured so as to output the electric signal, whichis output by the amplifying transistor 23, to the vertical signal line27 based on the selection signal. Specifically, as illustrated in FIG.5, the gate of the selection transistor 24 is connected to an addressline 28 to which the selection signal is supplied. Moreover, theselection transistor 24 is turned on when the selection signal issupplied, and as described above, the selection transistor 24 outputsthe output signal, which is amplified by the amplifying transistor 23,to the vertical signal line 27.

In the pixel transistor Tr, as illustrated in FIG. 5, the resettransistor 25 is configured so as to reset the gate potential of theamplifying transistor 23. Specifically, as illustrated in FIG. 5, thegate of the reset transistor 25 is electrically connected to a resetline 29 to which the reset signal is supplied. Moreover, the drain ofthe reset transistor 25 is electrically connected to the power supplyline Vdd, and the source of the reset transistor is electricallyconnected to the floating diffusion FD. In addition, the resettransistor 25 resets the gate potential of the amplifying transistor 23to a power supply voltage via the floating diffusion FD based on thereset signal which is sent from the reset line 29.

FIG. 6 is a timing chart illustrating a control signal which is sent tothe pixel transistor Tr of the pixel P when imaging is performed in thefirst embodiment of the present disclosure.

In FIG. 6, (a) illustrates a selection signal SEL which is input to thegate of the selection transistor 24. Moreover, (b) illustrates a resetsignal RST which is input to the gate of the reset transistor 25. Inaddition, (c) illustrates a transfer signal TG which is input to thegate of the transfer transistor 22 (refer to FIG. 5).

As illustrated in FIG. 6, when the imaging is performed, in a first timepoint t1, the selection transistor 24 is turned on while the selectionsignal SEL is set to a high level. Moreover, in a second time point t2,the reset transistor 25 is turned on while the reset signal RST is setto a high level. Thereby, the gate potential of the amplifyingtransistor 23 is reset (refer to FIG. 5).

In addition, as illustrated in FIG. 6, in a third time point t3, thereset transistor 25 is turned off while the reset signal RST is set to alow level. Moreover, thereafter, the voltage corresponding to the resetlevel is read to the column circuit as an output signal 14 (refer toFIGS. 2 and 5).

In addition, as illustrated in FIG. 6, in a fourth time point t4, thetransfer transistor 22 is turned on while the transfer signal TG is setto a high level. Thereby, the signal charge which is accumulated by thephotodiode 21 is transferred to the floating diffusion FD (refer to FIG.5).

In addition, as illustrated in FIG. 6, in a fifth time point t5, thetransfer transistor 22 is turned off while the transfer signal TG is setto a low level. Thereafter, the voltage of the signal levelcorresponding to the amount of the accumulated signal charge is read tothe column circuit 4 as an output signal (refer to FIGS. 2 and 5).

In the column circuit 14, a differential processing between the signalof the previously read reset level and the signal of the latterly readsignal level is preformed and the processed signal is accumulated (referto FIGS. 2 and 5).

Thereby, a fixed pattern noise, which is generated by variations or thelike of Vth in each transistor provided for each pixel P, is cancelledout.

Since each gate of the transistors 22, 24, and 25 is connected by a rowunit which includes a plurality of pixels P lined up in a horizontaldirection x, the operation driving the pixel P as described above issimultaneously performed with respect to the plurality of pixels P whichis lined up by the row unit.

Specifically, the pixels are sequentially selected in the perpendiculardirection by the horizontal line (pixel row) unit through the selectionsignal which is supplied by the above-described vertical drive circuit13. In addition, the transistors of each pixel P are controlled byvarious timing signals which are output from the timing generator 18.Therefore, the signals of each pixel are read to the column circuit 14for each column of the pixels P through the vertical signal line 27(refer to FIGS. 2 and 5).

Moreover, the signals accumulated by the column circuit 14 are selectedby the horizontal drive circuit 15 and sequentially output to theexternal output circuit 17 (refer to FIGS. 2 and 5).

In addition, the signal processing portion 44 performs the signalprocessing while having the signals obtained by the imaging as raw dataand generates a digital image (refer to FIG. 1).

(g) Wiring Layer 111

In the solid-state imaging device 1, as illustrated in FIG. 3, thewiring layer 111 is provided on the front surface (lower surface) of theside opposite to the rear surface (upper surface) on which each portionsuch as the light shielding film 60, the color filter CF, and themicrolens ML is provided in the semiconductor substrate 101.

The wiring layer 111 includes wirings 111 h and the insulating layer 111z and is configured so that the wirings 111 h are electrically connectedto each element in the insulating layer 111 z. The wiring layer 111 is aso-called multilayer wiring and formed by laminating alternativelyinterlayer insulating films configuring the insulating layer 111 z andwirings 111 h a plurality of times. Here, a plurality of wirings 111 hare formed to be laminated via the insulation layer 111 z so as tofunction as each wiring of the transfer line 26, the address line 28,the vertical signal line 27, the reset line 29, or the like illustratedin FIG. 5.

Moreover, in the wiring layer 111, the supporting substrate SS isprovided on the surface of the side opposite to the side on which thesemiconductor substrate 101 is positioned. For example, a substratewhich includes a silicon semiconductor having a thickness of severalhundred μm is provided as the supporting substrate SS.

(B) Manufacturing Method

Main portions of a method for manufacturing the above-describedsolid-state imaging device 1 will be described.

FIGS. 7 to 13 are diagrams illustrating the method of manufacturing thesolid-state imaging device in the first embodiment of the presentdisclosure.

Similarly to FIG. 3, each drawing is illustrated in a cross-section, andthe solid-state imaging device 1 illustrated in FIG. 3 or the like ismanufactured sequentially through processes illustrated in each drawing.

(a) Formation of Photodiode 21 or the like

First, as illustrated in FIG. 7, formation of the photodiode 21 or thelike is performed.

Here, the photodiode 21 is formed by ion-implanting impurities from thefront surface of the semiconductor substrate 101 including a singlecrystal silicon semiconductor. Moreover, after the pixel transistor Tr(not illustrated in FIG. 7) is formed on the front surface of thesemiconductor substrate 101, the wiring layer 111 is formed so as tocover the pixel transistor Tr. In addition, the supporting substrate SSis bonded to the front surface of the wiring layer 111.

Thereafter, for example, the semiconductor substrate 101 is thinned soas to have a thickness of about 10 to 20 μm. For example, the thinningis performed by grinding the substrate through a CMP method.

Moreover, the photodiode 21 and the pixel transistor Tr are formed on asemiconductor layer of a SOI substrate (not illustrated), similarly tothe above-described one; after the wiring layer 111 and the supportingsubstrate SS are provided, the thinning treatment may be performed.

(b) Formation of Trench TR

Next, as illustrated in FIG. 8, the trench TR is formed.

Here, the trench TR is formed at a portion which forms the pixelseparation portion 301 (refer to FIG. 3) in the semiconductor substrate101.

Specifically, as illustrated in FIG. 8, after a hard mask HM ispattern-processed on the rear surface (upper surface) of thesemiconductor substrate 101, the trench TR is formed by performing thepattern-processing with respect to the semiconductor substrate 101 byusing the hard mask HM. For example, the trench TR is formed so as tohave a depth of 0.3 to 3.0 μm by performing an etching processing of thesemiconductor substrate 101 by using a sheet-type dry etching apparatus.

(c) Removal of Hard Mask HM

Next, as illustrated in FIG. 9, the hard mask HM is removed.

Here, for example, the hard mask HM is removed from the rear surface(upper surface) of the semiconductor substrate 101 by performing anetching processing with respect to the hard mask HM. Thereby, the rearsurface (upper surface) of the semiconductor substrate 101 is exposed.

(d) Formation of Light Absorption Insulating Film 401

Next, as illustrated in FIG. 10, a light absorption insulating film 401is formed.

Here, in order to bury the inner portion of the trench TR which isformed in the semiconductor substrate 101, the light absorptioninsulating film 401 is formed by forming the film of an insulationmaterial, which absorbs the light incident to the light sensing surfaceJS, on the rear surface (upper surface) of the semiconductor substrate101.

In the present embodiment, the light absorption insulation film 401 isformed by forming the film of the insulation material which selectivelyabsorbs the light having the wavelength range of the shortest wavelengthin the light having a plurality of different wavelength ranges whichenters the light sensing surface JS via the color filter CF (refer toFIGS. 3 and 4). That is, the light absorption insulating film 401 isformed by forming the film of the insulation material which at leastselectively absorbs the blue light having the shortest wavelength amongcolored light which is transmitted by the red filter layer CFR, thegreen filter layer CFG, and the blue filter layer CFB.

Specifically, the light absorption insulating film 401 is formed byforming a silicon nitride film (SiN) through an ALD method.

For example, the light absorption insulating film 401 is formed byforming the silicon nitride film (SiN) according to the followingconditions.

-   -   SiH₂Cl₂ flow rate: 500 to 1500 sccm    -   NH₃ flow rate: 2000 to 4000 sccm    -   N₂ flow rate: 500 to 1000 sccm    -   RF Power: 100 to 500 W    -   Film Formation Temperature: 320 to 400° C.

(e) Formation of Pixel Separation Portion 301

Next, as illustrated in FIG. 11, the pixel separation portion 301 isformed.

Here, the pixel separation portion 301 is formed from the lightabsorption insulating film 401 by removing the upper surface portion ofthe light absorption insulating film 401 so as to expose the rearsurface (upper surface) of the semiconductor substrate 101.

For example, the rear surface (upper surface) of the semiconductorsubstrate 101 is exposed by performing a dry etching processing withrespect to the upper surface portion of the light absorption insulatingfilm 401. Thereby, the pixel separation portion 301, which is embeddedinto the trench TR of the semiconductor substrate 101, is formed.

Besides this, the pixel separation portion 301 may be formed byperforming a CMP processing with respect to the upper surface portion ofthe light absorption insulating film 401.

(f) Formation of Light Shielding Film 60

Next, as illustrated in FIG. 12, the light shielding film 60 is formed.

Here, the light shielding film 60 is formed so as to cover the entirerear surface (upper surface) of the semiconductor substrate 101 via theinsulating film SZ.

Specifically, the insulating film SZ is formed by forming the film ofthe insulation material on the entire rear surface (upper surface) ofthe semiconductor substrate 101. For example, the insulating film SZ isformed by forming a silicon oxide film so as to have a thickness of 100to 500 nm.

Moreover, the light shielding film 60 is formed by forming the film ofthe light shielding material on the entire upper surface of theinsulating film SZ. For example, the light shielding film 60 is formedby sequentially forming a titanium (Ti) film having the thickness of 10to 50 nm and a tungsten (W) film having the thickness of 100 to 300 nmthrough a sputtering method.

(g) Pattern Processing of Light Shielding Film 60

Next, as illustrated in FIG. 13, the light shielding film 60 ispattern-processed.

Here, the light shielding film 60 is pattern-processed so as to be apattern in which the upper portion of the pixel separation portion 301is covered and the portion of the light sensing surface JS of thephotodiode 21 is opened. That is, as illustrated in FIG. 4, the lightshielding film 60 is processed so that the planar shape is a pattern ofthe lattice shape.

Specifically, the light shielding film 60 is processed by performing adry etching processing.

(h) Formation of Planarized Film HT, Color Filter CF, and Microlens ML

Next, as illustrated in FIG. 3, each member of the planarized film HT,the color filter CF, and the microlens ML is formed.

Here, the planarized film HT is formed so as to evenly cover the rearsurface (upper surface) of the semiconductor substrate 101 on which thelight shielding film 60 is pattern-processed. For example, theplanarized film HT is formed by performing a heat curing treatment afterapplying an acrylic based heat curable resin through a spin-coatingmethod.

Moreover, as illustrated in FIG. 3, the color filter CF is formed on theupper surface of the planarized film HT.

For example, the color filter CF is formed by pattern-processing acoating film through a lithography technology after applying anapplication liquid including coloring matters such as pigments or dyesand photosensitive resins through a coating method such as thespin-coating method and forming the coating film.

Thereafter, as illustrated in FIG. 3, the microlens ML is provided onthe upper surface of the color filter CF. For example, the microlens MLis formed by deforming the pattern-processed resin into a lens shapethrough a reflow treatment after pattern-processing a photosensitiveresin film through a photolithography technology. Beside this, themicrolens ML may be formed by performing an etch-back processing whilehaving the resist pattern as a mask after forming a resist pattern of alens shape on a lens material film.

In this way, the “rear surface illumination type” of CMOS image sensoris completed.

(C) Conclusion

As described above, in the present embodiment, the plurality ofphotodiodes 21 which receive the incident light H through the lightsensing surface JS are provided so as to correspond to the plurality ofpixels P in the inner portion of the semiconductor substrate 101respectively. In addition, the pixel separation portion 301 whichelectrically separates the plurality of pixels P is embedded into theinner portion of the trench TR provided at the side portion of thephotodiode 21 in the side of the rear surface (upper surface) into whichthe incident light H enters in the semiconductor substrate 101 (refer toFIG. 3).

The pixel transistor Tr, which outputs the signal charge generated bythe photodiode 21 as the electric signal, is provided on the frontsurface (lower surface) of the side opposite to the rear surface (uppersurface) into which the incident light H enters in the semiconductorsubstrate 101. In addition, the wiring layer 111 is provided so as tocover the pixel transistor Tr in the front surface of the semiconductorsubstrate 101 (refer to FIG. 3).

The color filter CF, which is transmitted by the incident light H to thelight sensing surface JS, is provided on the side of the rear surface(upper surface) of the semiconductor substrate 101. Like the red filterlayer CFR, the green filter layer CFG, and the blue filter layer CFB ofthe color filter CF, a plurality of kinds of filter layers having ahigher transmissivity in light of wavelength ranges different to oneanother are disposed so as to be adjacent to one another correspondingto each of the plurality of pixels P (refer to FIG. 4).

In the case of the “rear surface illumination type”, when the pixelseparation portion 101 pb is formed by ion-implanting the impuritiesfrom the front surface (lower surface) side of the semiconductorsubstrate 101 (refer to FIG. 27), the “color mixing” in the vicinity ofthe rear surface (upper surface) of the semiconductor substrate 101 isoften generated. Particularly, the “color mixing” is often generated inthe short wavelength light such as blue. In addition to this, thesaturation charge accumulation amount (Qs) of the photodiode 21 isdecreased, and a dynamic range may be deteriorated.

However, in the present embodiment, the pixel separation portion 301 isprovided in the inner portion of the trench TR which is formed on therear surface (upper surface) side in the semiconductor substrate 101.Here, the pixel separation portion 301 is formed by an insulationmaterial which absorbs the light incident to the light sensing surfaceJS. Thereby, the separation between the pixels P can be realized withthe narrower width at the deeper region from the rear surface, and theelectric field in the vicinity of the rear surface can be strong.

In addition, in light having a plurality of wavelength ranges differentto one another which enters the light sensing surface JS via each of theplurality of kinds of filter layers CFR, CFG, and CFB configuring thecolor filter CF, the pixel separation portion 301 is formed so as toselectively absorb the light having some wavelength ranges. Here, thepixel separation portion 301 is formed so as to at least selectivelyabsorb the light having the wavelength range of the shortest wavelengthamong the plurality of different wavelength ranges in the plurality ofkinds of filter layers CFR, CFG, and CFB. That is, in colored lightwhich is transmitted by the red filter layer CFR, the green filter layerCFG, and the blue filter layer CFB, the pixel separation portion isformed so as to at least selectively absorb the blue light having theshortest wavelength.

Therefore, in the “rear surface illumination type” of the presentembodiment, since the pixel separation portion 301 selectively absorbsthe short wavelength light which is absorbed in the vicinity of the rearsurface of the semiconductor substrate 101 and obviously generates the“color mixing”, occurrence of the “color mixing” can be appropriatelyprevented. Moreover, since the saturation charge capacitance (saturationsignal amount) (Qs) can be increased, a dynamic range can be improved.Particularly, the effect can be appropriately exhibited in the portionwhich receives blue color.

Moreover, in the present embodiment, the pixel separation portion 301 isformed by a material which has the refractive index different from thatof the semiconductor substrate 101. Therefore, in the presentembodiment, sensitivity can be improved.

Particularly, in the present embodiment, since the pixel separationportion 301 is formed by the silicon nitride film which is formedthrough an ALD method, the effect can be appropriately exhibited.

The effect will be described in detail.

FIG. 14 is a graph illustrating the refractive index of single crystalSi. FIG. 15 is a graph illustrating the refractive index and theextinction coefficient of a SiN film. In FIGS. 14 and 15, a horizontalaxis indicates the wavelength, and a vertical axis indicates therefractive index or the extinction coefficient.

FIG. 16 is a graph illustrating a FTIR (Fourier Transform Infraredabsorption) spectrum of the SiN film. In FIG. 16, a horizontal axisindicates wavenumbers, and the vertical axis indicates absorbance.

As illustrated in FIG. 14, in a visible light region (360 to 830 nm),the refractive index of the single crystal Si configuring thesemiconductor substrate 101 (refer to FIG. 3) is about 4. In contrast,the refractive index of the SiN configuring the pixel separation portion301 (refer to FIG. 3) is about 2 as illustrated in FIG. 15. In this way,since the refractive index difference between the semiconductorsubstrate 101 and the pixel separation portion 301 is great, the entireincident light H entering the photodiode 21 is reflected at theinterface between the semiconductor substrate 101 and the pixelseparation portion 301. Moreover, the light reflected at the interfaceenters the photodiode 21 again and performs a photoelectric conversion.Therefore, in the present embodiment, sensitivity can be improved.

In addition, as illustrated in FIG. 15, the extinction coefficient ofthe SiN is increased in a region in which the wavelength is 400 nm orless. Moreover, as illustrated in FIG. 16, by a Si—H connection,absorption is generated with respect to the light in which thewavelength is 450 nm. Thereby, in the pixel separation portion 301configured by the SiN, the light having the shorter wavelength like theblue light, which is not reflected at the interface, can be selectivelyabsorbed.

Therefore, in the present embodiment, occurrence of the “color mixing”is prevented, and it is possible to improve color reproducibility in thecaptured color image.

Thus, in the present embodiment, it is possible to improve an imagequality.

(D) Modification

In the above, the case where the pixel separation portion 301 (refer toFIG. 3) is formed by a silicon nitride (SiN) is described. However, thepresent disclosure is not limited thereto.

The pixel separation portion 301 may be formed by using an inorganiclight absorption material such as SiO₂, SiCN, and SiOC and may absorbthe light of the shorter wavelength side.

Moreover, as described below, the pixel separation portion 301 may beformed by an organic light absorption material.

(D-1) Modification 1-1

The pixel separation portion 301 may be formed by using a photosensitiveresin (black resist), which contains a black pigment such as a carbonblack, as a light absorption material of an insulator.

FIG. 17 is a graph illustrating the transmissivity of the photosensitiveresin containing the black pigment.

In FIG. 17, a horizontal axis indicates the wavelength and a verticalaxis indicates the transmissivity.

FIG. 17 illustrates a case of a light absorption material of thefollowing condition.

-   -   Material Name of Black Pigment: a carbon based pigment or a        mixture based pigment of a copper phthalocyanine based pigment        and a pyridone azo based pigment.    -   Material Name of Photosensitive Resin: acrylic material    -   Content of Black Pigment: 10 to 50%    -   Content of Photosensitive Resin: 10 to 70%    -   Thickness: 0.3 to 3 μm

Moreover, in FIG. 17, #11 illustrates the result in the case where themixture based pigment of the copper phthalocyanine based pigment and thepyridone azo based pigment is used. #12 illustrates the result in thecase where the carbon based pigment is used.

As can be seen from the result illustrated in FIG. 17, due to the factthat the photosensitive resin (black resist) containing the blackpigment is used as a light absorption material, the pixel separationportion 301 having the lower transmissivity over the whole visible lightregion can be formed.

Therefore, since the pixel separation portion 301 absorbs and shieldsthe light from one pixel toward the photodiodes 21 of other pixels,occurrence of the “color mixing” can be appropriately prevented, and itis possible to improve color reproducibility in the captured colorimage.

Thus, it is possible to improve an image quality.

Besides this, in the present modification, since the photosensitiveresin (black resist) containing the black pigment is used as the lightabsorption material, an embedding property into the trench ispreferable.

(D-2) Modification 1-2

Similarly to the color filter CF of three primary colors describedabove, the pixel separation portion 301 may be formed by using a colorfilter material containing primary color system pigments of red, green,and blue as the light absorption material of the insulator. Moreover,the color filter material including complementary color system pigmentsof yellow, magenta, and cyan may be used as the light absorptionmaterial of the insulator. That is, the pixel separation portion 301 maybe formed by using color resists such as a red resist, a green resist, ablue resist, a yellow resist, a magenta resist, and a cyan resist.

FIGS. 18A to 18C are graphs illustrating a transmissivity of aphotosensitive resin containing a primary color system pigment. In FIGS.18A to 18C, FIG. 18A represents the case of a red filter material (redresist), FIG. 18B represents the case of a green filter material (greenresist), and FIG. 18C represents the case of a blue filter material(blue resist).

FIGS. 19A to 19C are graphs illustrating the transmissivity of aphotosensitive resin containing a complementary color system pigment. InFIGS. 19A to 19C, FIG. 19A represents the case of a yellow filtermaterial (yellow resist), FIG. 19B represents the case of a magentafilter material (magenta resist), and FIG. 19C represents the case of acyan filter material (cyan resist).

In FIGS. 18A to 18C and 19A to 19C, a horizontal axis indicates awavelength and a vertical axis indicates a transmissivity.

For example, FIGS. 18A to 18C and 19A to 19C illustrate a case of alight absorption material of the following condition.

-   -   Material Name of Each Pigment

Blue: a triphenylmethane based pigment

Green: an azo (chromium complex) based and triphenylmethane basedpigment

Red: an azo (chromium complex) based pigment

Cyan: a copper phthalocyanine based pigment

Magenta: a xanthene pigment

Yellow: a pyridone azo pigment

-   -   Material Name of Photosensitive Resin: a novolac based resin    -   Content of Each Pigment: 10 to 50%    -   Content of Photosensitive Resin: 10 to 70%

As can be seen from the result illustrated in FIGS. 18A to 18C and 19Ato 19C, due to the fact that the photosensitive resin containing eachpigment is used as the light absorption material, the pixel separationportion 301 having the lower transmissivity in a portion of a visiblelight region can be formed.

For example, like blue, in a case where the light having the shorterwavelength in visible light is absorbed by the pixel separation portion301, the pixel separation portion 301 is formed by a material used inthe green filter, the red filter, and the yellow filter. Since thetransmissivity of the material is lower with respect to the light havingthe shorter wavelength in visible light, the material can appropriatelyabsorb and shield the light of the wavelength.

Like green, in a case where the light having an intermediate wavelengthin visible light is absorbed by the pixel separation portion 301, thepixel separation portion 301 is formed by a material used in the bluefilter, the red filter, and the magenta filter. Since the transmissivityof the material is lower with respect to the light having anintermediate wavelength in visible light, the material can appropriatelyabsorb and shield the light of the wavelength.

Like red, in a case where the light having the longer wavelength invisible light is absorbed by the pixel separation portion 301, the pixelseparation portion 301 is formed by a material used in the blue filterand the green filter. Since the transmissivity of the material is lowerwith respect to the light having the longer wavelength in visible light,the material can appropriately absorb and shield the light of thewavelength.

Thereby, since the pixel separation portion 301 absorbs and shields thelight from one pixel toward the photodiodes 21 of other pixels,occurrence of the “color mixing” can be appropriately prevented, and itis possible to improve color reproducibility in the captured colorimage.

Thus, it is possible to improve an image quality.

Moreover, like the present embodiment, the photolithographycharacteristic in the case where the color resist is used is moresuitable that in the case where the black resist is used. Since theblack resist absorbs light, the photolithography in the deeper regionmay be difficult to perform.

2. Second Embodiment

(A) Device Configuration or the Like

FIG. 20 is a diagram illustrating a main portion of a solid-stateimaging device in a second embodiment of the present disclosure.

Similarly to FIG. 3, FIG. 20 illustrates the cross-section of the pixelP.

As illustrated in FIG. 20, a pinning layer 501 is provided in thepresent embodiment. Except for this point and those related to thepoint, the present embodiment is similar to the first embodiment.Thereby, description is appropriately omitted with respect to theoverlapped portions.

As illustrated in FIG. 20, the pinning layer 501 is formed so as tocover around the pixel separation portion 301 which divides between aplurality of pixels P in the side of the rear surface (upper surface) ofthe semiconductor substrate 101.

Specifically, the pinning layer 501 is formed so as to cover the surfaceof the inside of the trench, which is formed on the rear surface (uppersurface) side in the semiconductor substrate 101, with a constantthickness. In addition, the pixel separation portion 301 is provided soas to be embedded to the inner portion of the trench which is covered bythe pinning layer 501.

Here, the pinning layer 501 is formed by using a high dielectricconstant material which has a negative fixed charge so as to form apositive charge (hole) accumulation region in the interface portion withthe semiconductor substrate 101 and suppress occurrence of a darkcurrent. Since the pinning layer 501 is formed so as to have a negativefixed charge and an electric field is added to the interface with thesemiconductor substrate 101 by the negative fixed charge, the positivecharge (hole) accumulation region is formed.

(B) Manufacturing Method

Main portions of a method for manufacturing the above-describedsolid-state imaging device will be described.

FIGS. 21 to 23 are diagrams illustrating a method of manufacturing thesolid-state imaging device in the second embodiment of the presentdisclosure.

Similarly to FIG. 20, FIGS. 21 to FIG. 23 are illustrated in across-section, and the solid-state imaging device illustrated in FIG. 20is manufactured sequentially through each process illustrated in FIGS.21 to 23.

Before carrying out each process illustrated in FIGS. 21 to 23,similarly to the first embodiment, the formations of the photodiode 21or the like, the formation of the trench TR, and the removal of the hardmask HM are performed as illustrated in FIGS. 7 to 9.

(a) Formation of Pinning Layer 501

Next, as illustrated in FIG. 21, the pinning layer 501 is formed.

Here, the pinning layer 501 is formed so as to cover the surface onwhich the photodiode 21 is formed and the inside surface of the trenchTR in the rear surface (upper surface) of the semiconductor substrate101.

For example, the pinning layer 501 is provided by forming a hafniumoxide film (HfO₂ film) of 1 to 20 nm in thickness by the ALD methodunder a condition of a film formation temperature of 200 to 300° C.

In addition to the hafnium oxide film (HfO₂ film), the pinning layer 501can be formed by using various materials. For example, the pinning layer501 is formed so as to include at least one of oxides of elementalhafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium,lanthanoids, or the like.

Here, it is preferable to form the pinning layer 501 by using a materialwhich has a higher flat band voltage than a silicon oxide film (SiO₂film).

For example, it is preferable to form the pinning layer 501 by using ahigh dielectric constant (high-k) material below. Moreover, in thefollowing, ΔVfb indicates a value which subtracts the flat band voltageVfb (SiO₂) of SiO₂ from the flat band voltage Vfb (High-k) of the high-kmaterial (that is, ΔVfb=Vfb(High-k)−Vfb(SiO₂)).

-   -   Al₂O₃ (ΔVfb=4 to 6 V)    -   HfO₂ (ΔVfb=2 to 3 V)    -   ZrO₂ (ΔVfb=2 to 3 v)    -   TiO₂ (ΔVfb=3 to 4 V)    -   Ta₂O₅ (ΔVfb=3 to 4 V)    -   MaO₂ (ΔVfb=1.5 to 2.5 V)

(b) Formation of Light Absorption Insulating Film 401

Next, as illustrated in FIG. 22, the light absorption insulating film401 is formed.

Here, a film of an insulation material which absorbs light is formed onthe rear surface (upper surface) of the semiconductor substrate 101 soas to bury the inner portion of the trench TR which is covered by thepinning layer 501. Thereby, the light absorption insulating film 401 isformed.

For example, similarly to the case of the first embodiment, the lightabsorption film 401 is formed by forming a silicon nitride film (SiN) bythe ALD method.

(c) Formation of Pixel Separation Portion 301

Next, as illustrated in FIG. 23, the pixel separation portion 301 isformed.

Here, in the light absorption insulating material film 401, the portionwhich is embedded to the inner portion of the trench TR of thesemiconductor substrate 101 remains, and the portion on the rear surface(upper surface) of the semiconductor substrate 101 is removed.Similarly, in the pinning layer 501, the portion which is embedded tothe inner portion of the trench TR of the semiconductor substrate 101remains, and the portion on the rear surface (upper surface) of thesemiconductor substrate 101 is removed. Thereby, the rear surface (uppersurface) of the semiconductor substrate 101 is exposed, and the pixelseparation portion 301 is formed from the light absorption insulatingfilm 401.

For example, the rear surface (upper surface) of the semiconductorsubstrate 101 is exposed by performing a dry etching processing. Besidesthis, the pixel separation portion 301 may be formed by performing a CMPprocessing.

(d) Formation of Light Shielding Film 60 or the Like

Next, as illustrated in FIG. 12, each member such as the light shieldingfilm 60 is formed.

Here, similarly to the case of the first embodiment, the light shieldingfilm 60 is pattern-processed and formed. Each member of the planarizedfilm HT, the color filter CF, and the microlens ML is formed.

Thereby, the “rear surface illumination type” of CMOS image sensor iscompleted.

(C) Conclusion

As described above, in the present embodiment, similarly to the case ofthe first embodiment, the pixel separation portion 301 is provided inthe trench TR which is formed on the rear surface (upper surface) sidein the semiconductor substrate 101. Here, the pixel separation portion301 is formed by an insulation material which absorbs the light incidentto the light sensing surface JS.

Therefore, similarly to the first embodiment, in the present embodiment,it is possible to improve an image quality.

In addition, in the present embodiment, the pinning layer 501 is formedso as to cover the surface of the inner portion of the trench TR in thesemiconductor substrate 101. Therefore, since positive holes (hole) areexcited in the interface with the semiconductor substrate 101 by thepinning layer 501, occurrences of a dark current and a white point canbe suppressed.

Therefore, in the present embodiment, it is possible to further improvean image quality.

Moreover, similarly to the modifications illustrated in the firstembodiment, also in the present embodiment, the pixel separation portion301 may be formed by using various light absorption materials.

3. Third Embodiment

(A) Device Configuration or the Like

FIG. 24 is a diagram illustrating a main portion of a solid-stateimaging device in a third embodiment of the present disclosure.

Similarly to FIG. 3, FIG. 24 illustrates the cross-section of the pixelP.

As illustrated in FIG. 24, in the present embodiment, a configuration ofa pixel separation portion 301 c is different from the case of the firstembodiment. Except for this point and those related to the point, thepresent embodiment is similar to the first embodiment. Thereby,description is appropriately omitted with respect to the overlappedportions.

As illustrated in FIG. 24, similarly to the case of the firstembodiment, the pixel separation portion 301 c is embedded to the innerportion of the semiconductor substrate 101 in the rear surface (uppersurface) side of the semiconductor substrate 101. That is, the pixelseparation portion 301 c is provided in the trench TR which is formed onthe rear surface (upper surface) side in the semiconductor substrate101.

Moreover, the pixel separation portion 301 c is formed by an insulationmaterial which absorbs the light incident to the light sensing surfaceJS.

In the present embodiment, as illustrated in FIG. 24, the pixelseparation portion 301 c includes a first light absorption portion 311and a second light absorption portion 312 unlike the case of the firstembodiment.

In the pixel separation portion 301 c, the first light absorptionportion 311 and the second light absorption portion 312 are providedfrom the rear surface (upper surface) side of the semiconductorsubstrate 101 in the trench TR which is provided in the semiconductorsubstrate 101. That is, in the pixel separation portion 301 c, thesecond light absorption portion 312 is formed at the bottom portion sideof the trench TR which is provided in the semiconductor substrate 101,and the first light absorption portion 311 is formed so as to belaminated on the second light absorption portion 312 in the upperportion side of the trench TR.

The first light absorption portion 311 and the second light absorptionportion 312 are each formed by a light absorption material differentfrom each other, and the wavelength ranges which absorb light aredifferent from each other.

Specifically, in the pixel separation portion 301 c, the first lightabsorption portion 311 is formed so as to absorb the light having thewavelength range of the shortest wavelength in the light having aplurality of different wavelength ranges which enters the light sensingsurface JS via the color filter CF.

For example, the first light absorption portion 311 is formed by using asilicon nitride film (SiN), which is formed by an ALD method, as a lightabsorption material of an insulator. That is, the transmissivity of thefirst light absorption portion 311 is lower with respect to a blue lighthaving the shorter wavelength, and the first light absorption portion311 is formed so as to selectively absorb the shorter wavelength light(refer to FIG. 15).

In contrast, the second light absorption portion 312 is formed so as toabsorb the light of the wavelength range having the longer wavelengththan the wavelength of the light absorbed by the first light absorptionportion 311 in the light having a plurality of different wavelengthranges which enters the light sensing surface JS via the color filterCF.

For example, the second light absorption portion 312 is formed by usinga color filter material (red resist), which contains a primary colorsystem pigment of red, as a light absorption material of an insulator.That is, the second light absorption portion 312 is formed so that thetransmissivity is higher for red light having the longer wavelength andis lower for green light and blue light having a shorter wavelength thanthat of the red light (refer to FIG. 18A).

In the above-described pixel separation portion 301 c, the second lightabsorption portion 312 is formed on the bottom portion of the trench TRwhich is provided in the semiconductor substrate 101. Thereafter, thefirst light absorption portion 311 is formed so as to be laminated onthe second light absorption portion 312. Thereby, the pixel separationportion 301 c is formed.

For example, the first light absorption portion 311 and the second lightabsorption portion 312 are formed according to the following condition.

-   -   Thickness of First Light Absorption Portion 311: 0.3 to 1 μm.    -   Thickness of Second Light Absorption Portion 312: 1 to 2 μm.

(B) Conclusion

As described above, similarly to the case of the first embodiment, inthe present embodiment, the pixel separation portion 301 c is providedin the trench TR which is formed on the rear surface (upper surface)side in the semiconductor substrate 101. Here, the pixel separationportion 301 c is formed by an insulation material which absorbs thelight incident to the light sensing surface JS.

Thereby, similarly to the first embodiment, in the present embodiment,it is possible to improve an image quality.

Moreover, in the present embodiment, the pixel separation portion 301 cincludes the first light absorption portion 311 and the second lightabsorption portion 312. The wavelength ranges, which absorb light in thefirst light absorption portion 311 and the second light absorptionportion 312, are different from each other.

Thereby, in the present embodiment, since the pixel separation portion301 c can absorb the light in a wider wavelength range, occurrence ofthe “color mixing” can be appropriately prevented.

Moreover, in the present embodiment, in the pixel separation portion 301c, the first light absorption portion 311 and the second lightabsorption portion 312 are provided from the rear surface (uppersurface) side in the trench TR which is provided in the semiconductorsubstrate 101.

Here, the second light absorption portion 312 is formed so as to absorbso as to absorb the light of the wavelength range having the longerwavelength than the wavelength of the light absorbed by the first lightabsorption portion 311. That is, the pixel separation portion 301 c isformed so that the transmissivity with respect to the light having theshorter wavelength is lower in the portion of the rear surface (uppersurface) side into which the incident light H enters in thesemiconductor substrate 101, and the transmissivity with respect to thelight having the longer wavelength is lower in the deeper portion thanthe rear surface (upper surface) side portion.

Thereby, in the present embodiment, the first light absorption portion311 can appropriately absorb the light of the shorter wavelength (forexample, blue light) which reaches the vicinity of the rear surface ofthe semiconductor substrate 101 but does not reach the deeper portion(refer to FIG. 15 or the like). Moreover, the second light absorptionportion 312 can appropriately absorb the light of the longer wavelength(for example, green light) which reaches the deeper portion of thesemiconductor substrate 101 (refer to FIG. 18A). Thereby, in the presentembodiment, occurrence of the “color mixing” can be effectivelyprevented.

(C) Modification

In the above, in the pixel separation portion 301 c, the case where thefirst light absorption portion 311 is formed by a silicon nitride (SiN)and the second light absorption portion 312 is formed by using a redresist is described. However, the present disclosure is not limitedthereto. Each portion may be formed by using an inorganic lightabsorption material such as SiO₂, SiCN, and SiOC.

In addition, both the first light absorption portion 311 and the secondlight absorption portion 312 may be formed by an organic lightabsorption material.

(C-1) Modification 3-1

For example, the first light absorption portion 311 is formed by using ared resist, and the second light absorption portion 312 is formed byusing a blue resist. Thereby, the first light absorption portion 311 canappropriately absorb the shorter wavelength light (for example, bluelight) which reaches the vicinity of the rear surface of thesemiconductor substrate 101 but does not reach the deeper portion (referto FIG. 18A or the like). Moreover, the second light absorption portion312 can appropriately absorb the light of the longer wavelength (forexample, green light and red light) which reaches the deeper portion ofthe semiconductor substrate 101 (refer to FIG. 18C).

Besides this, similarly to the modification illustrated in the firstembodiment, the first light absorption portion 311 and the second lightabsorption portion 312 may each be formed by using various lightabsorption materials.

(C-2) Modification 3-2

In addition, the material which forms the first light absorption portion311 and the second light absorption portion 312 may be changed accordingto the combination of the wavelength ranges of the light which arereceived by each of adjacent pixels P in between each of the adjacentpixels P.

Moreover, the thickness (depth) which forms the first light absorptionportion 311 and the second light absorption portion 312 may be changedaccording to the combination of the wavelength ranges of the light whichare received by each of the adjacent pixels P in between each of theadjacent pixels P.

For example, as illustrated in FIG. 4, the first light absorptionportion 311 is formed by using a blue resist between the pixel P whichreceives a red light and the pixel P which receives a green light.Thereby, the green light which has the shorter wavelength than the redlight is absorbed by the first light absorption portion 311 of the upperportion.

Moreover, the second light absorption portion 312 is formed by a greenresist. Therefore, the red light which has the longer wavelength thanthe green light is absorbed by the second light absorption portion 312of the lower portion.

In this case, it is preferable that the first light absorption portion311 of the upper portion and the second light absorption portion 312 ofthe lower portion are formed according to the following condition.

-   -   Thickness of First Light Absorption Portion 311 (blue resist):        0.3 to 1 μm    -   Thickness of Second Light Absorption Portion 312 (green resist):        1 to 2 μm

In addition, as illustrated in FIG. 4, the first light absorptionportion 311 is formed by using a red resist between the pixel P whichreceives the blue light and the pixel p which receives the green light.

Thereby, the blue light which has the shorter wavelength than the greenlight is absorbed by the first light absorption portion 311 of the upperportion. Moreover, the second light absorption portion 312 is formed bya blue resist. Therefore, the green light which has the longerwavelength than the blue light is absorbed by the second lightabsorption portion 312 of the lower portion.

In this case, it is preferable that the first light absorption portion311 of the upper portion and the second light absorption portion 312 ofthe lower portion are formed according to the following condition.

-   -   Thickness of First Light Absorption Portion 311 (red resist):        0.3 to 1 μm    -   Thickness of Second Light Absorption Portion 312 (blue resist):        1 to 2 μm

As described above, it is preferable that the first light absorptionportion 311 of the upper portion is formed by using a light absorptionmaterial which absorbs the light having the shorter wavelength and thesecond light absorption portion 312 of the lower portion is formed by alight absorption material which absorbs the light having the longerwavelength. That is, it is preferable that the second light absorptionportion 312 is formed so as to absorb the light of the wavelength rangehaving the longer wavelength than the wavelength of the light absorbedby the first light absorption portion 311.

Thereby, the incidence of the light having the shorter wavelength ispossible in the upper portion of the semiconductor substrate 101, andthe incidence of the light having the longer wavelength is possible inthe lower portion.

4. Fourth Embodiment

(A) Device Configuration or the Like

FIG. 25 is a diagram illustrating a main portion of a solid-stateimaging device in a fourth embodiment of the present disclosure.

Similarly to FIG. 24, FIG. 25 illustrates the cross-section of the pixelP.

As illustrated in FIG. 25, in the present embodiment, a configuration ofa pixel separation portion 301 d is different from the case of the thirdembodiment. Except for this point and those related to the point, thepresent embodiment is similar to the third embodiment. Thereby,description is appropriately omitted with respect to the overlappedportions.

As illustrated in FIG. 25, similarly to the case of the thirdembodiment, the pixel separation portion 301 d is embedded to the innerportion of the semiconductor substrate 101 in the rear surface (uppersurface) side of the semiconductor substrate 101. That is, the pixelseparation portion 301 d is provided in the trench TR which is formed onthe rear surface (upper surface) side in the semiconductor substrate101.

Moreover, the pixel separation portion 301 d is formed by an insulationmaterial which absorbs the light incident to the light sensing surfaceJS.

In the present embodiment, as illustrated in FIG. 25, the pixelseparation portion 301 d includes a third light absorption portion 313in addition to the first light absorption portion 311 and the secondlight absorption portion 312 unlike the case of the third embodiment.

In the pixel separation portion 301 d, the first light absorptionportion 311, the second light absorption portion 312, and the thirdlight absorption portion 313 are provided from the rear surface (uppersurface) side of the semiconductor substrate 101 in the trench TR whichis provided in the semiconductor substrate 101. That is, in the pixelseparation portion 301 d, the third light absorption portion 313 isformed at the bottom portion side of the trench TR which is provided inthe semiconductor substrate 101. In addition, the second lightabsorption portion 312 is formed so as to be laminated on the thirdlight absorption portion 313 in inner portion of the trench TR.Moreover, the first light absorption portion 311 is formed so as to belaminated on the second light absorption portion 312 in the upperportion side of the trench TR.

The first light absorption portion 311, the second light absorptionportion 312, and the third light absorption portion 313 each are formedby a light absorption material different from one another, and thewavelength ranges which absorb the light are different from one another.

For example, the first light absorption portion 311 is formed by using acolor filter material (green resist), which contains a primary colorsystem pigment of green, as a light absorption material of an insulator.That is, the first light absorption portion 311 is formed so that thetransmissivity is higher in the green light having an intermediatewavelength and is lower in the light having the shorter wavelength orthe longer wavelength than that of the green light (refer to FIG. 18B).

For example, the second light absorption portion 312 is formed by usinga color filter material (blue resist), which contains a primary colorsystem pigment of blue, as a light absorption material of an insulator.That is, the second light absorption portion 312 is formed so that thetransmissivity is higher in the blue light having the shorter wavelengthand is lower in the light having the longer wavelength than that of theblue light (refer to FIG. 18C).

For example, the third light absorption portion 313 is formed by using acolor filter material (red resist), which contains a primary colorsystem pigment of a red, as a light absorption material of an insulator.That is, the third light absorption portion 313 is formed so that thetransmissivity is higher in the red light having the longer wavelengthand is lower in the light having the shorter wavelength than that of thered light (refer to FIG. 18A).

In the above-described pixel separation portion 301 d, the third lightabsorption portion 313 is formed on the bottom portion of the trench TRwhich is provided in the semiconductor substrate 101. In addition, thesecond light absorption portion 312 is formed so as to be laminated onthe third light absorption portion 313. Thereafter, the first lightabsorption portion 311 is formed so as to be laminated on the secondlight absorption portion 312. Thereby, the pixel separation portion 301d is formed.

For example, the first light absorption portion 311, the second lightabsorption portion 312, and the third light absorption portion 313 areformed according to the following condition.

-   -   Thickness of First Light Absorption Portion 311: 0.3 to 1 μm.    -   Thickness of Second Light Absorption Portion 312: 1 to 2 μm.    -   Thickness of Third Light Absorption Portion 313: 1 to 2 μm.

(B) Conclusion

As described above, similarly to the case of the first embodiment, inthe present embodiment, the pixel separation portion 301 d is providedin the trench TR which is formed on the rear surface (upper surface)side in the semiconductor substrate 101. Here, the pixel separationportion 301 d is formed by an insulation material which absorbs thelight incident to the light sensing surface JS.

Thereby, similarly to the first embodiment, in the present embodiment,it is possible to improve an image quality.

Moreover, in the pixel separation portion 301 d of the presentembodiment, the wavelength ranges, which absorb light in each of thefirst light absorption portion 311, the second light absorption portion312, and the third light absorption portion 313, are different from oneanother. In addition, in the pixel separation portion 301 d, the firstlight absorption portion 311, the second light absorption portion 312,and the third light absorption portion 313 are provided from the rearsurface (upper surface) side of the semiconductor substrate 101 in thetrench TR which is provided in the semiconductor substrate 101. Thereby,in the present embodiment, since the pixel separation portion 301 d canabsorb the light of the wider wavelength range, occurrence of the “colormixing” can be appropriately prevented.

(C) Modification

In the above, in the pixel separation portion 301 d, the case where thefirst light absorption portion 311, the second light absorption portion312, and the third light absorption portion 313 are each formed by usingan organic light absorption material is described. However, the presentdisclosure is not limited thereto.

Similarly to other embodiments, each portion may be formed by using aninorganic light absorption material such as SiN, SiO₂, SiCN, and SiOC.

Moreover in the above, the first light absorption portion 311 is formedby a green resist (G), the second light absorption portion 312 is formedby a blue resist (B), and the third light absorption portion 313 isformed by a red resist (R). However, the present disclosure is notlimited thereto.

For example, the first light absorption portion 311 may be formed by ared resist (R), the second light absorption portion 312 may be formed bya green resist (G), and the third light absorption portion 313 may beformed by a blue resist (B). That is, the second light absorptionportion 312 may be formed so as to absorb the light of the wavelengthrange having the longer wavelength than the wavelength of the lightabsorbed by the first light absorption portion 311, and the third lightabsorption portion 313 may be formed so as to absorb the light of thewavelength range having the longer wavelength than the wavelength of thelight absorbed by the second light absorption portion 312. In this case,similarly to the case of the third embodiment, the pixel separationportion 301 d is formed so that the transmissivity of the light havingthe shorter wavelength is lower in the portion of the rear surface(upper surface) side into which the incident light H enters and thetransmissivity of the light having the longer wavelength is lower in thedeeper portion in the semiconductor substrate 101. Thereby, similarly tothe third embodiment, occurrence of the “color mixing” can beeffectively prevented.

Moreover, in the above, the case where the pixel separation portionincludes total three light absorption portions is described. However,the present disclosure is not limited thereto. The pixel separationportion may include more than three light absorption portions.

5. Fifth Embodiment

(A) Device Configuration

FIG. 26 is a diagram illustrating a main portion of a solid-stateimaging device in a fifth embodiment of the present disclosure.

Similarly to FIG. 3, FIG. 26 illustrates the cross-section of the pixelP.

As illustrated in FIG. 26, the solid-state imaging device is a “frontsurface illumination type”. That is, the solid-state imaging device isconfigured so that the wiring layer 111 is provided in the front surface(upper surface in FIG. 26) side of the semiconductor substrate 101 andthe light sensing surface JS receives the incident light H incident fromthe front surface side. Moreover, the supporting substrate SS (refer toFIG. 3) is provided. Except for this point and those related to thepoint, the present embodiment is similar to the first embodiment.Thereby, description is appropriately omitted with respect to theoverlapped portions.

In the present embodiment, as illustrated in FIG. 26, in the solid-stateimaging device, the photodiode 21 and the pixel separation portion 301are provided in the inner portion of the semiconductor substrate 101.

As illustrated in FIG. 26, the photodiode 21 is provided so that then-type semiconductor region 101 n is positioned in the inner portion ofthe p-type semiconductor region 101 pa and 101 pc at the front surface(upper surface) side of the semiconductor substrate 101.

As illustrated in FIG. 26, the pixel separation portion 301 is embeddedto the inner portion of the semiconductor substrate 101 in the frontsurface (upper surface) side of the semiconductor substrate 101. Thatis, the pixel separation portion 301 is provided in the trench TR whichis formed on the front surface (upper surface) side in the semiconductorsubstrate 101. Similarly to the first embodiment, the pixel separationportion 301 is formed by an insulation material which absorbs the lightincident to the light sensing surface JS.

The light shielding film 60 is provided on the front surface (uppersurface) of the semiconductor substrate 101 similarly to the firstembodiment, and the wiring layer 111 is provided so as to cover thelight shielding film 60.

In the wiring layer 111, the wirings 111 h are provided on a portionother than the upper portion of the light sensing surface JS in theinsulation layer 111 z.

Moreover, similarly to the first embodiment, the color filter CF and themicrolens ML are provided on the upper surface of the wiring layer 111.

Although not illustrated in FIG. 26, the pixel transistor Tr illustratedin FIG. 5 is provided on the front surface (upper surface) of thesemiconductor substrate 101. The wiring layer 111 is provided so as tocover the pixel transistor Tr.

(B) Conclusion

As described above, in the present embodiment, similarly to the case ofthe first embodiment, the pixel separation portion 301 is provided inthe trench TR which is formed on the rear surface (upper surface) sidein the semiconductor substrate 101. Here, the pixel separation portion301 is formed by an insulation material which absorbs the light incidentto the light sensing surface JS.

Therefore, in the present embodiment, similarly to the first embodiment,it is possible to improve an image quality.

As described above, the solid-state imaging device of the presentembodiment is the “front surface illumination type”. As described above,in the case of the “front surface illumination type”, since the pixelseparation portion is formed by ion-implanting impurities from the frontsurface side into which the incident light enters in the semiconductorsubstrate, it is difficult to improve the saturation charge accumulationamount (Qs) of the pixel which receives the light having the longerwavelength such as a red light.

However, in the present embodiment, the pixel separation portion 301 isembedded to the inner portion of the trench TR which is provided at theside portions of the photodiode 21 in the semiconductor substrate 101.Thereby, since the pixel P can be separated at the deeper region withrespect to the light sensing surface JS, particularly, in the photodiode21 which receives the red light, the saturation charge accumulationamount (Qs) can be great, and a dynamic range can be improved.

Moreover, in the present embodiment, the case where the pixel separationportion 301 is formed similarly to the case of the first embodiment isdescribed. However, the present disclosure is not limited to thereto.That is, the pixel separation portion may be formed similarly to thecases of other embodiments and modifications.

6. Others

When the present disclosure is performed, the present disclosure is notlimited to the above-described embodiments. That is, the presentdisclosure can adopt various modifications.

In the above-described embodiments, the case where the presentdisclosure is applied to the camera is described. However, the presentdisclosure is not limited thereto. That is, the present disclosure maybe also applied to other electronic apparatuses including a solid-stateimaging device such as a scanner or a copier.

In the above-described embodiments, the case where four kinds of thetransfer transistor, the amplifying transistor, the selectiontransistor, and the reset transistor are provided as the pixeltransistor is described. However, the present disclosure is not limitedthereto. For example, the present disclosure may be also applied to acase where three kinds of the transfer transistor, the amplifyingtransistor, and the reset transistor are provided as the pixeltransistor.

In the above-described embodiments, the case where each of the transfertransistor, the amplifying transistor, the selection transistor, and thereset transistor is provided to one photodiode one by one is described.However, the present disclosure is not limited thereto. For example, thepresent disclosure may be also applied to a case where each of theamplifying transistor, the selection transistor, and the resettransistor is provided to a plurality of photodiodes one by one.

Moreover, the present disclosure may be applied to a CCD type imagesensor in addition to the CMOS type image sensor.

In addition, the above-described embodiments may be appropriatelycombined.

Moreover, the solid-state imaging device 1 in the above-describedembodiments corresponds to the solid-state imaging device of the presentdisclosure. In addition, the photodiode 21 in the above-describedembodiments corresponds to the photoelectric conversion portion of thepresent disclosure. Moreover, the camera 40 in the above-describedembodiments corresponds to the electronic apparatus of the presentdisclosure. In addition, the light shielding film 60 in theabove-described embodiments corresponds to the light shielding film ofthe present disclosure. Moreover, the semiconductor substrate 101 in theabove-described embodiments corresponds to the semiconductor substrateof the present disclosure. In addition, the wiring layer 111 in theabove-described embodiments corresponds to the wiring layer of thepresent disclosure. Moreover, the pixel separation portion 301, 301 c,and 301 d in the above-described embodiments corresponds to the pixelseparation portion of the present disclosure. In addition, the firstlight absorption portion 311 in the above-described embodimentscorresponds to the first light absorption portion of the presentdisclosure. Moreover, the second light absorption portion 312 in theabove-described embodiments corresponds to the second light absorptionportion of the present disclosure. In addition, the third lightabsorption portion 313 in the above-described embodiments corresponds tothe third light absorption portion of the present disclosure. Inaddition, the pinning layer 501 in the above-described embodimentscorresponds to the pinning layer of the present disclosure. Moreover,the color filter CF in the above-described embodiments corresponds tothe color filter of the present disclosure. In addition, the blue filterlayer CFB in the above-described embodiments corresponds to the filterlayer or the first filter layer of the present disclosure. Moreover, thegreen filter layer CFG in the above-described embodiments corresponds tothe filter layer or the second filter layer of the present disclosure.In addition, the red filter layer CFR in the above-described embodimentscorresponds to the filter layer or the third filter layer of the presentdisclosure. Moreover, the light sensing surface JS in theabove-described embodiments corresponds to the light sensing surface ofthe present disclosure. In addition, the pixel P in the above-describedembodiments corresponds to the pixel of the present disclosure.Moreover, the trench TR in the above-described embodiments correspondsto the trench of the present disclosure. In addition, the pixeltransistor Tr in the above-described embodiments corresponds to thepixel transistor of the present disclosure.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-038443 filed in theJapan Patent Office on Feb. 24, 2011, the entire contents of which arehereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A solid-state imaging device comprising: asemiconductor substrate having a light sensing surface and a non-lightsensing surface; a plurality of photoelectric conversion portions eachprovided to correspond to each of a plurality of pixels in thesemiconductor substrate and receiving incident light through the lightsensing surface; a pixel separation portion that is embedded into atrench provided on a side portion of the photoelectric conversionportion and electrically separates the plurality of pixels in a side ofan incident surface of the semiconductor substrate into which theincident light enters, wherein the pixel separation portion is formed byan insulation material which absorbs the incident light entering thelight sensing surface; a wiring layer provided on the non-light sensingsurface of the semiconductor substrate; a silicon oxide insulating filmwith a light sensing surface and a non-light sensing surface, whereinboth the light sensing surface and the non-light sensing surface areentirely planar; a substantially transparent planarized film disposed onat least a portion of the light sensing surface of the silicon oxideinsulating film; and a light shielding film with a light incidentsurface and a non-light incident surface, wherein the light shieldingfilm is disposed between the silicon oxide insulating film and thesubstantially transparent planarized film, and wherein the non-lightsensing surface of the light shielding film is in direct contact with atleast a portion of the light sensing surface of the silicon oxideinsulating film.
 2. The solid-state imaging device according to claim 1,further comprising: a color filter through which the incident light istransmitted to the light sensing surface, wherein the color filterincludes a plurality of kinds of filter layers having a highertransmissivity with respect to light of wavelength ranges different fromone another are disposed so as to be adjacent to one anothercorresponding to each of the plurality of pixels, and the pixelseparation portion is formed so as to selectively absorb light having atleast one wavelength range among a plurality of different wavelengthranges in the plurality of kinds of filter layers.
 3. The solid-stateimaging device according to claim 2, wherein the pixel separationportion is formed so as to at least selectively absorb light of awavelength range of the shortest wavelength among a plurality ofdifferent wavelength ranges in the plurality of kinds of filter layers.4. The solid-state imaging device according to claim 3, wherein a firstfilter layer having a high transmissivity with respect to light of afirst wavelength range of the shortest wavelength and a second filterlayer having a high transmissivity with respect to light of a secondwavelength range having a longer wavelength than a wavelength of thefirst wavelength range among the plurality of wavelength ranges are atleast provided as the plurality of kinds of filter layers in the colorfilter, each of the first filter layer and the second filter layer isdisposed so as to be adjacent to each other corresponding to each of theplurality of pixels, and the pixel separation portion is formed so as toat least selectively absorb light of the first wavelength range.
 5. Thesolid-state imaging device according to claim 4, wherein the pixelseparation portion includes, a first light absorption portion thatselectively absorbs the light of the first wavelength range, and asecond light absorption portion that selectively absorbs the light ofthe second wavelength range, and the first light absorption portion andthe second light absorption portion are provided so as to be laminatedin the trench.
 6. The solid-state imaging device according to claim 5,wherein the second light absorption portion is formed on a bottom sideof the trench and the first light absorption portion is formed so as tobe laminated on the second light absorption portion in the upper portionside of the trench in the pixel separation portion.
 7. The solid-stateimaging device according to claim 5, wherein a third filter layer havinga high transmissivity with respect to light of a third wavelength rangewhich has a longer wavelength than a wavelength of the second wavelengthrange is further provided as the plurality of kinds of filter layers inthe color filter, the third filter layer is disposed along with each ofthe first filter layer and the second filter layer so as to be adjacentto one another corresponding to each of the plurality of pixels, thepixel separation portion further includes a third light absorptionportion which selectively absorbs light of the third wavelength range,and the third light absorption portion is provided along with the firstlight absorption portion and the second light absorption portion so asto be laminated in the trench.
 8. The solid-state imaging deviceaccording to claim 7, wherein the third light absorption portion isformed on a bottom side of the trench, the second light absorptionportion is formed so as to be laminated on the third light absorptionportion, and the first light absorption is formed so as to be laminatedon the second light absorption portion, in the pixel separation portion.9. The solid-state imaging device according to claim 1, furthercomprising: a pixel transistor provided on the non-light sensing surfaceof the semiconductor substrate and outputs a signal charge generated bythe photoelectric conversion portion as an electric signal, wherein thepixel transistor is in electrical contact with the wiring layer.
 10. Thesolid-state imaging device according to claim 1, wherein the pixelseparation portion is formed by a material having a refractive indexdifferent from a refractive index of the semiconductor substrate. 11.The solid-state imaging device according to claim 1, further comprising:a pinning layer that is formed so as to cover a surface in the trench inthe semiconductor substrate.
 12. The solid-state imaging deviceaccording to claim 4, wherein the pixel separation portion is formed bya silicon nitride film which is formed by an ALD (Atomic LayerDeposition) method.
 13. The solid-state imaging device according toclaim 4, wherein the pixel separation portion is formed by a resin whichincludes a black pigment.
 14. A method of manufacturing a solid-stateimaging device comprising: providing a semiconductor substrate having alight sensing surface and a non-light sensing surface; providing aplurality of photoelectric conversion portions which receive incidentlight through a light sensing surface so as to correspond to a pluralityof pixels in the semiconductor substrate; forming a pixel separationportion that electrically separates the plurality of pixels so as to beembedded into a trench provided on a side portion of the photoelectricconversion portion in a side of an incident surface of the semiconductorsubstrate into which the incident light enters, wherein the pixelseparation portion is formed by an insulation material which absorbs theincident light entering the light sensing surface when forming the pixelseparation portion; providing a wiring layer on the non-light sensingsurface of the semiconductor substrate; providing a silicon oxideinsulating film with a light sensing surface and a non-light sensingsurface, wherein both the light sensing surface and the non-lightsensing surface are entirely planar; providing a substantiallytransparent planarized film disposed on at least a portion of the lightsensing surface of the silicon oxide insulating film; and providing alight shielding film with a light incident surface and a non-lightincident surface, wherein the light shielding film is disposed betweenthe silicon oxide insulating film and the substantially transparentplanarized film, and wherein the non-light sensing surface of the lightshielding film is in direct contact with at least a portion of the lightsensing surface of the silicon oxide insulating film.
 15. An electricapparatus comprising: a semiconductor substrate having a light sensingsurface and a non-light sensing surface; a plurality of photoelectricconversion portions each provided to correspond to each of a pluralityof pixels in a semiconductor substrate and receiving incident lightthrough a light sensing surface, a pixel separation portion that isembedded into a trench provided on a side portion of the photoelectricconversion portion and electrically separates the plurality of pixels ina side of an incident surface of the semiconductor substrate into whichthe incident light enters, and wherein the pixel separation portion isformed by an insulation material which absorbs the incident lightentering the light sensing surface; a wiring layer disposed on thenon-light sensing surface of the semiconductor substrate; a siliconoxide insulating film with a light sensing surface and a non-lightsensing surface, wherein both the light sensing surface and thenon-light sensing surface are entirely planar; a substantiallytransparent planarized film disposed on at least a portion of the lightsensing surface of the silicon oxide insulating film; and a lightshielding film with a light incident surface and a non-light incidentsurface, wherein the light shielding film is disposed between thesilicon oxide insulating film and the substantially transparentplanarized film, and wherein the non-light sensing surface of the lightshielding film is in direct contact with at least a portion of the lightsensing surface of the silicon oxide insulating film.